Maybe I’m old, but I loved hosting Open Arena, Teeworlds and Cube 2: Sauerbraten.

Terraria. It’s a sort of hybrid between a minecraft 2d and an action RPG, really fun game with lots of content.

You can play it as standalone or as co-op and the server component is included in the game for you to host it if you want.

Tho If by interesting you mean MMOs, there are emulators for a few of them, WoW is my favorite (TrinityCore, AzerothCore), but know that opening them up to public use is illegal (copyright violation).

Edit: added github links to wow emulators.

These are ones I keep coming back to: Farming Simulator, Satisfactory, and Valheim. I’ve also kept up a V-Rising server at times because my friends like it, but I’m not as into that game. Always on the lookout for games to host for friends, so I’m glad I stumbled upon this thread! Found a few in here I’m going to try out.

There’s always Valheim…

But I host Titanfall servers. People are able to play on them using the Northstar client, a mod for the game that lets you connect to community servers, as well as mod the game in general.

Project Zomboid is worth looking at. It’s not my kind of game, but it’s great at what it is (top down zombie survival crafring)

Minecraft, Veloren, Valheim, Core Keeper